1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Macros for manipulating and testing page->flags 4 */ 5 6 #ifndef PAGE_FLAGS_H 7 #define PAGE_FLAGS_H 8 9 #include <linux/types.h> 10 #include <linux/bug.h> 11 #include <linux/mmdebug.h> 12 #ifndef __GENERATING_BOUNDS_H 13 #include <linux/mm_types.h> 14 #include <generated/bounds.h> 15 #endif /* !__GENERATING_BOUNDS_H */ 16 17 /* 18 * Various page->flags bits: 19 * 20 * PG_reserved is set for special pages. The "struct page" of such a page 21 * should in general not be touched (e.g. set dirty) except by its owner. 22 * Pages marked as PG_reserved include: 23 * - Pages part of the kernel image (including vDSO) and similar (e.g. BIOS, 24 * initrd, HW tables) 25 * - Pages reserved or allocated early during boot (before the page allocator 26 * was initialized). This includes (depending on the architecture) the 27 * initial vmemmap, initial page tables, crashkernel, elfcorehdr, and much 28 * much more. Once (if ever) freed, PG_reserved is cleared and they will 29 * be given to the page allocator. 30 * - Pages falling into physical memory gaps - not IORESOURCE_SYSRAM. Trying 31 * to read/write these pages might end badly. Don't touch! 32 * - The zero page(s) 33 * - Pages not added to the page allocator when onlining a section because 34 * they were excluded via the online_page_callback() or because they are 35 * PG_hwpoison. 36 * - Pages allocated in the context of kexec/kdump (loaded kernel image, 37 * control pages, vmcoreinfo) 38 * - MMIO/DMA pages. Some architectures don't allow to ioremap pages that are 39 * not marked PG_reserved (as they might be in use by somebody else who does 40 * not respect the caching strategy). 41 * - Pages part of an offline section (struct pages of offline sections should 42 * not be trusted as they will be initialized when first onlined). 43 * - MCA pages on ia64 44 * - Pages holding CPU notes for POWER Firmware Assisted Dump 45 * - Device memory (e.g. PMEM, DAX, HMM) 46 * Some PG_reserved pages will be excluded from the hibernation image. 47 * PG_reserved does in general not hinder anybody from dumping or swapping 48 * and is no longer required for remap_pfn_range(). ioremap might require it. 49 * Consequently, PG_reserved for a page mapped into user space can indicate 50 * the zero page, the vDSO, MMIO pages or device memory. 51 * 52 * The PG_private bitflag is set on pagecache pages if they contain filesystem 53 * specific data (which is normally at page->private). It can be used by 54 * private allocations for its own usage. 55 * 56 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O 57 * and cleared when writeback _starts_ or when read _completes_. PG_writeback 58 * is set before writeback starts and cleared when it finishes. 59 * 60 * PG_locked also pins a page in pagecache, and blocks truncation of the file 61 * while it is held. 62 * 63 * page_waitqueue(page) is a wait queue of all tasks waiting for the page 64 * to become unlocked. 65 * 66 * PG_uptodate tells whether the page's contents is valid. When a read 67 * completes, the page becomes uptodate, unless a disk I/O error happened. 68 * 69 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and 70 * file-backed pagecache (see mm/vmscan.c). 71 * 72 * PG_error is set to indicate that an I/O error occurred on this page. 73 * 74 * PG_arch_1 is an architecture specific page state bit. The generic code 75 * guarantees that this bit is cleared for a page when it first is entered into 76 * the page cache. 77 * 78 * PG_hwpoison indicates that a page got corrupted in hardware and contains 79 * data with incorrect ECC bits that triggered a machine check. Accessing is 80 * not safe since it may cause another machine check. Don't touch! 81 */ 82 83 /* 84 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break 85 * locked- and dirty-page accounting. 86 * 87 * The page flags field is split into two parts, the main flags area 88 * which extends from the low bits upwards, and the fields area which 89 * extends from the high bits downwards. 90 * 91 * | FIELD | ... | FLAGS | 92 * N-1 ^ 0 93 * (NR_PAGEFLAGS) 94 * 95 * The fields area is reserved for fields mapping zone, node (for NUMA) and 96 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like 97 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP). 98 */ 99 enum pageflags { 100 PG_locked, /* Page is locked. Don't touch. */ 101 PG_referenced, 102 PG_uptodate, 103 PG_dirty, 104 PG_lru, 105 PG_active, 106 PG_workingset, 107 PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */ 108 PG_error, 109 PG_slab, 110 PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/ 111 PG_arch_1, 112 PG_reserved, 113 PG_private, /* If pagecache, has fs-private data */ 114 PG_private_2, /* If pagecache, has fs aux data */ 115 PG_writeback, /* Page is under writeback */ 116 PG_head, /* A head page */ 117 PG_mappedtodisk, /* Has blocks allocated on-disk */ 118 PG_reclaim, /* To be reclaimed asap */ 119 PG_swapbacked, /* Page is backed by RAM/swap */ 120 PG_unevictable, /* Page is "unevictable" */ 121 #ifdef CONFIG_MMU 122 PG_mlocked, /* Page is vma mlocked */ 123 #endif 124 #ifdef CONFIG_ARCH_USES_PG_UNCACHED 125 PG_uncached, /* Page has been mapped as uncached */ 126 #endif 127 #ifdef CONFIG_MEMORY_FAILURE 128 PG_hwpoison, /* hardware poisoned page. Don't touch */ 129 #endif 130 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT) 131 PG_young, 132 PG_idle, 133 #endif 134 __NR_PAGEFLAGS, 135 136 /* Filesystems */ 137 PG_checked = PG_owner_priv_1, 138 139 /* SwapBacked */ 140 PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */ 141 142 /* Two page bits are conscripted by FS-Cache to maintain local caching 143 * state. These bits are set on pages belonging to the netfs's inodes 144 * when those inodes are being locally cached. 145 */ 146 PG_fscache = PG_private_2, /* page backed by cache */ 147 148 /* XEN */ 149 /* Pinned in Xen as a read-only pagetable page. */ 150 PG_pinned = PG_owner_priv_1, 151 /* Pinned as part of domain save (see xen_mm_pin_all()). */ 152 PG_savepinned = PG_dirty, 153 /* Has a grant mapping of another (foreign) domain's page. */ 154 PG_foreign = PG_owner_priv_1, 155 156 /* SLOB */ 157 PG_slob_free = PG_private, 158 159 /* Compound pages. Stored in first tail page's flags */ 160 PG_double_map = PG_private_2, 161 162 /* non-lru isolated movable page */ 163 PG_isolated = PG_reclaim, 164 }; 165 166 #ifndef __GENERATING_BOUNDS_H 167 168 struct page; /* forward declaration */ 169 170 static inline struct page *compound_head(struct page *page) 171 { 172 unsigned long head = READ_ONCE(page->compound_head); 173 174 if (unlikely(head & 1)) 175 return (struct page *) (head - 1); 176 return page; 177 } 178 179 static __always_inline int PageTail(struct page *page) 180 { 181 return READ_ONCE(page->compound_head) & 1; 182 } 183 184 static __always_inline int PageCompound(struct page *page) 185 { 186 return test_bit(PG_head, &page->flags) || PageTail(page); 187 } 188 189 #define PAGE_POISON_PATTERN -1l 190 static inline int PagePoisoned(const struct page *page) 191 { 192 return page->flags == PAGE_POISON_PATTERN; 193 } 194 195 #ifdef CONFIG_DEBUG_VM 196 void page_init_poison(struct page *page, size_t size); 197 #else 198 static inline void page_init_poison(struct page *page, size_t size) 199 { 200 } 201 #endif 202 203 /* 204 * Page flags policies wrt compound pages 205 * 206 * PF_POISONED_CHECK 207 * check if this struct page poisoned/uninitialized 208 * 209 * PF_ANY: 210 * the page flag is relevant for small, head and tail pages. 211 * 212 * PF_HEAD: 213 * for compound page all operations related to the page flag applied to 214 * head page. 215 * 216 * PF_ONLY_HEAD: 217 * for compound page, callers only ever operate on the head page. 218 * 219 * PF_NO_TAIL: 220 * modifications of the page flag must be done on small or head pages, 221 * checks can be done on tail pages too. 222 * 223 * PF_NO_COMPOUND: 224 * the page flag is not relevant for compound pages. 225 */ 226 #define PF_POISONED_CHECK(page) ({ \ 227 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \ 228 page; }) 229 #define PF_ANY(page, enforce) PF_POISONED_CHECK(page) 230 #define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page)) 231 #define PF_ONLY_HEAD(page, enforce) ({ \ 232 VM_BUG_ON_PGFLAGS(PageTail(page), page); \ 233 PF_POISONED_CHECK(page); }) 234 #define PF_NO_TAIL(page, enforce) ({ \ 235 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \ 236 PF_POISONED_CHECK(compound_head(page)); }) 237 #define PF_NO_COMPOUND(page, enforce) ({ \ 238 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \ 239 PF_POISONED_CHECK(page); }) 240 241 /* 242 * Macros to create function definitions for page flags 243 */ 244 #define TESTPAGEFLAG(uname, lname, policy) \ 245 static __always_inline int Page##uname(struct page *page) \ 246 { return test_bit(PG_##lname, &policy(page, 0)->flags); } 247 248 #define SETPAGEFLAG(uname, lname, policy) \ 249 static __always_inline void SetPage##uname(struct page *page) \ 250 { set_bit(PG_##lname, &policy(page, 1)->flags); } 251 252 #define CLEARPAGEFLAG(uname, lname, policy) \ 253 static __always_inline void ClearPage##uname(struct page *page) \ 254 { clear_bit(PG_##lname, &policy(page, 1)->flags); } 255 256 #define __SETPAGEFLAG(uname, lname, policy) \ 257 static __always_inline void __SetPage##uname(struct page *page) \ 258 { __set_bit(PG_##lname, &policy(page, 1)->flags); } 259 260 #define __CLEARPAGEFLAG(uname, lname, policy) \ 261 static __always_inline void __ClearPage##uname(struct page *page) \ 262 { __clear_bit(PG_##lname, &policy(page, 1)->flags); } 263 264 #define TESTSETFLAG(uname, lname, policy) \ 265 static __always_inline int TestSetPage##uname(struct page *page) \ 266 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); } 267 268 #define TESTCLEARFLAG(uname, lname, policy) \ 269 static __always_inline int TestClearPage##uname(struct page *page) \ 270 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); } 271 272 #define PAGEFLAG(uname, lname, policy) \ 273 TESTPAGEFLAG(uname, lname, policy) \ 274 SETPAGEFLAG(uname, lname, policy) \ 275 CLEARPAGEFLAG(uname, lname, policy) 276 277 #define __PAGEFLAG(uname, lname, policy) \ 278 TESTPAGEFLAG(uname, lname, policy) \ 279 __SETPAGEFLAG(uname, lname, policy) \ 280 __CLEARPAGEFLAG(uname, lname, policy) 281 282 #define TESTSCFLAG(uname, lname, policy) \ 283 TESTSETFLAG(uname, lname, policy) \ 284 TESTCLEARFLAG(uname, lname, policy) 285 286 #define TESTPAGEFLAG_FALSE(uname) \ 287 static inline int Page##uname(const struct page *page) { return 0; } 288 289 #define SETPAGEFLAG_NOOP(uname) \ 290 static inline void SetPage##uname(struct page *page) { } 291 292 #define CLEARPAGEFLAG_NOOP(uname) \ 293 static inline void ClearPage##uname(struct page *page) { } 294 295 #define __CLEARPAGEFLAG_NOOP(uname) \ 296 static inline void __ClearPage##uname(struct page *page) { } 297 298 #define TESTSETFLAG_FALSE(uname) \ 299 static inline int TestSetPage##uname(struct page *page) { return 0; } 300 301 #define TESTCLEARFLAG_FALSE(uname) \ 302 static inline int TestClearPage##uname(struct page *page) { return 0; } 303 304 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \ 305 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname) 306 307 #define TESTSCFLAG_FALSE(uname) \ 308 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname) 309 310 __PAGEFLAG(Locked, locked, PF_NO_TAIL) 311 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) 312 PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND) 313 PAGEFLAG(Referenced, referenced, PF_HEAD) 314 TESTCLEARFLAG(Referenced, referenced, PF_HEAD) 315 __SETPAGEFLAG(Referenced, referenced, PF_HEAD) 316 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD) 317 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD) 318 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD) 319 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD) 320 TESTCLEARFLAG(Active, active, PF_HEAD) 321 PAGEFLAG(Workingset, workingset, PF_HEAD) 322 TESTCLEARFLAG(Workingset, workingset, PF_HEAD) 323 __PAGEFLAG(Slab, slab, PF_NO_TAIL) 324 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL) 325 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */ 326 327 /* Xen */ 328 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND) 329 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND) 330 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND); 331 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND); 332 333 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) 334 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) 335 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) 336 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL) 337 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL) 338 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL) 339 340 /* 341 * Private page markings that may be used by the filesystem that owns the page 342 * for its own purposes. 343 * - PG_private and PG_private_2 cause releasepage() and co to be invoked 344 */ 345 PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY) 346 __CLEARPAGEFLAG(Private, private, PF_ANY) 347 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY) 348 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY) 349 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY) 350 351 /* 352 * Only test-and-set exist for PG_writeback. The unconditional operators are 353 * risky: they bypass page accounting. 354 */ 355 TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL) 356 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL) 357 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL) 358 359 /* PG_readahead is only used for reads; PG_reclaim is only for writes */ 360 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL) 361 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL) 362 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND) 363 TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND) 364 365 #ifdef CONFIG_HIGHMEM 366 /* 367 * Must use a macro here due to header dependency issues. page_zone() is not 368 * available at this point. 369 */ 370 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p)) 371 #else 372 PAGEFLAG_FALSE(HighMem) 373 #endif 374 375 #ifdef CONFIG_SWAP 376 static __always_inline int PageSwapCache(struct page *page) 377 { 378 #ifdef CONFIG_THP_SWAP 379 page = compound_head(page); 380 #endif 381 return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags); 382 383 } 384 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) 385 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) 386 #else 387 PAGEFLAG_FALSE(SwapCache) 388 #endif 389 390 PAGEFLAG(Unevictable, unevictable, PF_HEAD) 391 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD) 392 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD) 393 394 #ifdef CONFIG_MMU 395 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL) 396 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL) 397 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL) 398 #else 399 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked) 400 TESTSCFLAG_FALSE(Mlocked) 401 #endif 402 403 #ifdef CONFIG_ARCH_USES_PG_UNCACHED 404 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND) 405 #else 406 PAGEFLAG_FALSE(Uncached) 407 #endif 408 409 #ifdef CONFIG_MEMORY_FAILURE 410 PAGEFLAG(HWPoison, hwpoison, PF_ANY) 411 TESTSCFLAG(HWPoison, hwpoison, PF_ANY) 412 #define __PG_HWPOISON (1UL << PG_hwpoison) 413 extern bool set_hwpoison_free_buddy_page(struct page *page); 414 #else 415 PAGEFLAG_FALSE(HWPoison) 416 static inline bool set_hwpoison_free_buddy_page(struct page *page) 417 { 418 return 0; 419 } 420 #define __PG_HWPOISON 0 421 #endif 422 423 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT) 424 TESTPAGEFLAG(Young, young, PF_ANY) 425 SETPAGEFLAG(Young, young, PF_ANY) 426 TESTCLEARFLAG(Young, young, PF_ANY) 427 PAGEFLAG(Idle, idle, PF_ANY) 428 #endif 429 430 /* 431 * On an anonymous page mapped into a user virtual memory area, 432 * page->mapping points to its anon_vma, not to a struct address_space; 433 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h. 434 * 435 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled, 436 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON 437 * bit; and then page->mapping points, not to an anon_vma, but to a private 438 * structure which KSM associates with that merged page. See ksm.h. 439 * 440 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable 441 * page and then page->mapping points a struct address_space. 442 * 443 * Please note that, confusingly, "page_mapping" refers to the inode 444 * address_space which maps the page from disk; whereas "page_mapped" 445 * refers to user virtual address space into which the page is mapped. 446 */ 447 #define PAGE_MAPPING_ANON 0x1 448 #define PAGE_MAPPING_MOVABLE 0x2 449 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE) 450 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE) 451 452 static __always_inline int PageMappingFlags(struct page *page) 453 { 454 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0; 455 } 456 457 static __always_inline int PageAnon(struct page *page) 458 { 459 page = compound_head(page); 460 return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0; 461 } 462 463 static __always_inline int __PageMovable(struct page *page) 464 { 465 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) == 466 PAGE_MAPPING_MOVABLE; 467 } 468 469 #ifdef CONFIG_KSM 470 /* 471 * A KSM page is one of those write-protected "shared pages" or "merged pages" 472 * which KSM maps into multiple mms, wherever identical anonymous page content 473 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any 474 * anon_vma, but to that page's node of the stable tree. 475 */ 476 static __always_inline int PageKsm(struct page *page) 477 { 478 page = compound_head(page); 479 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) == 480 PAGE_MAPPING_KSM; 481 } 482 #else 483 TESTPAGEFLAG_FALSE(Ksm) 484 #endif 485 486 u64 stable_page_flags(struct page *page); 487 488 static inline int PageUptodate(struct page *page) 489 { 490 int ret; 491 page = compound_head(page); 492 ret = test_bit(PG_uptodate, &(page)->flags); 493 /* 494 * Must ensure that the data we read out of the page is loaded 495 * _after_ we've loaded page->flags to check for PageUptodate. 496 * We can skip the barrier if the page is not uptodate, because 497 * we wouldn't be reading anything from it. 498 * 499 * See SetPageUptodate() for the other side of the story. 500 */ 501 if (ret) 502 smp_rmb(); 503 504 return ret; 505 } 506 507 static __always_inline void __SetPageUptodate(struct page *page) 508 { 509 VM_BUG_ON_PAGE(PageTail(page), page); 510 smp_wmb(); 511 __set_bit(PG_uptodate, &page->flags); 512 } 513 514 static __always_inline void SetPageUptodate(struct page *page) 515 { 516 VM_BUG_ON_PAGE(PageTail(page), page); 517 /* 518 * Memory barrier must be issued before setting the PG_uptodate bit, 519 * so that all previous stores issued in order to bring the page 520 * uptodate are actually visible before PageUptodate becomes true. 521 */ 522 smp_wmb(); 523 set_bit(PG_uptodate, &page->flags); 524 } 525 526 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL) 527 528 int test_clear_page_writeback(struct page *page); 529 int __test_set_page_writeback(struct page *page, bool keep_write); 530 531 #define test_set_page_writeback(page) \ 532 __test_set_page_writeback(page, false) 533 #define test_set_page_writeback_keepwrite(page) \ 534 __test_set_page_writeback(page, true) 535 536 static inline void set_page_writeback(struct page *page) 537 { 538 test_set_page_writeback(page); 539 } 540 541 static inline void set_page_writeback_keepwrite(struct page *page) 542 { 543 test_set_page_writeback_keepwrite(page); 544 } 545 546 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY) 547 548 static __always_inline void set_compound_head(struct page *page, struct page *head) 549 { 550 WRITE_ONCE(page->compound_head, (unsigned long)head + 1); 551 } 552 553 static __always_inline void clear_compound_head(struct page *page) 554 { 555 WRITE_ONCE(page->compound_head, 0); 556 } 557 558 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 559 static inline void ClearPageCompound(struct page *page) 560 { 561 BUG_ON(!PageHead(page)); 562 ClearPageHead(page); 563 } 564 #endif 565 566 #define PG_head_mask ((1UL << PG_head)) 567 568 #ifdef CONFIG_HUGETLB_PAGE 569 int PageHuge(struct page *page); 570 int PageHeadHuge(struct page *page); 571 bool page_huge_active(struct page *page); 572 #else 573 TESTPAGEFLAG_FALSE(Huge) 574 TESTPAGEFLAG_FALSE(HeadHuge) 575 576 static inline bool page_huge_active(struct page *page) 577 { 578 return 0; 579 } 580 #endif 581 582 583 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 584 /* 585 * PageHuge() only returns true for hugetlbfs pages, but not for 586 * normal or transparent huge pages. 587 * 588 * PageTransHuge() returns true for both transparent huge and 589 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be 590 * called only in the core VM paths where hugetlbfs pages can't exist. 591 */ 592 static inline int PageTransHuge(struct page *page) 593 { 594 VM_BUG_ON_PAGE(PageTail(page), page); 595 return PageHead(page); 596 } 597 598 /* 599 * PageTransCompound returns true for both transparent huge pages 600 * and hugetlbfs pages, so it should only be called when it's known 601 * that hugetlbfs pages aren't involved. 602 */ 603 static inline int PageTransCompound(struct page *page) 604 { 605 return PageCompound(page); 606 } 607 608 /* 609 * PageTransCompoundMap is the same as PageTransCompound, but it also 610 * guarantees the primary MMU has the entire compound page mapped 611 * through pmd_trans_huge, which in turn guarantees the secondary MMUs 612 * can also map the entire compound page. This allows the secondary 613 * MMUs to call get_user_pages() only once for each compound page and 614 * to immediately map the entire compound page with a single secondary 615 * MMU fault. If there will be a pmd split later, the secondary MMUs 616 * will get an update through the MMU notifier invalidation through 617 * split_huge_pmd(). 618 * 619 * Unlike PageTransCompound, this is safe to be called only while 620 * split_huge_pmd() cannot run from under us, like if protected by the 621 * MMU notifier, otherwise it may result in page->_mapcount < 0 false 622 * positives. 623 */ 624 static inline int PageTransCompoundMap(struct page *page) 625 { 626 return PageTransCompound(page) && atomic_read(&page->_mapcount) < 0; 627 } 628 629 /* 630 * PageTransTail returns true for both transparent huge pages 631 * and hugetlbfs pages, so it should only be called when it's known 632 * that hugetlbfs pages aren't involved. 633 */ 634 static inline int PageTransTail(struct page *page) 635 { 636 return PageTail(page); 637 } 638 639 /* 640 * PageDoubleMap indicates that the compound page is mapped with PTEs as well 641 * as PMDs. 642 * 643 * This is required for optimization of rmap operations for THP: we can postpone 644 * per small page mapcount accounting (and its overhead from atomic operations) 645 * until the first PMD split. 646 * 647 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up 648 * by one. This reference will go away with last compound_mapcount. 649 * 650 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap(). 651 */ 652 static inline int PageDoubleMap(struct page *page) 653 { 654 return PageHead(page) && test_bit(PG_double_map, &page[1].flags); 655 } 656 657 static inline void SetPageDoubleMap(struct page *page) 658 { 659 VM_BUG_ON_PAGE(!PageHead(page), page); 660 set_bit(PG_double_map, &page[1].flags); 661 } 662 663 static inline void ClearPageDoubleMap(struct page *page) 664 { 665 VM_BUG_ON_PAGE(!PageHead(page), page); 666 clear_bit(PG_double_map, &page[1].flags); 667 } 668 static inline int TestSetPageDoubleMap(struct page *page) 669 { 670 VM_BUG_ON_PAGE(!PageHead(page), page); 671 return test_and_set_bit(PG_double_map, &page[1].flags); 672 } 673 674 static inline int TestClearPageDoubleMap(struct page *page) 675 { 676 VM_BUG_ON_PAGE(!PageHead(page), page); 677 return test_and_clear_bit(PG_double_map, &page[1].flags); 678 } 679 680 #else 681 TESTPAGEFLAG_FALSE(TransHuge) 682 TESTPAGEFLAG_FALSE(TransCompound) 683 TESTPAGEFLAG_FALSE(TransCompoundMap) 684 TESTPAGEFLAG_FALSE(TransTail) 685 PAGEFLAG_FALSE(DoubleMap) 686 TESTSETFLAG_FALSE(DoubleMap) 687 TESTCLEARFLAG_FALSE(DoubleMap) 688 #endif 689 690 /* 691 * For pages that are never mapped to userspace (and aren't PageSlab), 692 * page_type may be used. Because it is initialised to -1, we invert the 693 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and 694 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and 695 * low bits so that an underflow or overflow of page_mapcount() won't be 696 * mistaken for a page type value. 697 */ 698 699 #define PAGE_TYPE_BASE 0xf0000000 700 /* Reserve 0x0000007f to catch underflows of page_mapcount */ 701 #define PAGE_MAPCOUNT_RESERVE -128 702 #define PG_buddy 0x00000080 703 #define PG_offline 0x00000100 704 #define PG_kmemcg 0x00000200 705 #define PG_table 0x00000400 706 707 #define PageType(page, flag) \ 708 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE) 709 710 static inline int page_has_type(struct page *page) 711 { 712 return (int)page->page_type < PAGE_MAPCOUNT_RESERVE; 713 } 714 715 #define PAGE_TYPE_OPS(uname, lname) \ 716 static __always_inline int Page##uname(struct page *page) \ 717 { \ 718 return PageType(page, PG_##lname); \ 719 } \ 720 static __always_inline void __SetPage##uname(struct page *page) \ 721 { \ 722 VM_BUG_ON_PAGE(!PageType(page, 0), page); \ 723 page->page_type &= ~PG_##lname; \ 724 } \ 725 static __always_inline void __ClearPage##uname(struct page *page) \ 726 { \ 727 VM_BUG_ON_PAGE(!Page##uname(page), page); \ 728 page->page_type |= PG_##lname; \ 729 } 730 731 /* 732 * PageBuddy() indicates that the page is free and in the buddy system 733 * (see mm/page_alloc.c). 734 */ 735 PAGE_TYPE_OPS(Buddy, buddy) 736 737 /* 738 * PageOffline() indicates that the page is logically offline although the 739 * containing section is online. (e.g. inflated in a balloon driver or 740 * not onlined when onlining the section). 741 * The content of these pages is effectively stale. Such pages should not 742 * be touched (read/write/dump/save) except by their owner. 743 */ 744 PAGE_TYPE_OPS(Offline, offline) 745 746 /* 747 * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on 748 * pages allocated with __GFP_ACCOUNT. It gets cleared on page free. 749 */ 750 PAGE_TYPE_OPS(Kmemcg, kmemcg) 751 752 /* 753 * Marks pages in use as page tables. 754 */ 755 PAGE_TYPE_OPS(Table, table) 756 757 extern bool is_free_buddy_page(struct page *page); 758 759 __PAGEFLAG(Isolated, isolated, PF_ANY); 760 761 /* 762 * If network-based swap is enabled, sl*b must keep track of whether pages 763 * were allocated from pfmemalloc reserves. 764 */ 765 static inline int PageSlabPfmemalloc(struct page *page) 766 { 767 VM_BUG_ON_PAGE(!PageSlab(page), page); 768 return PageActive(page); 769 } 770 771 static inline void SetPageSlabPfmemalloc(struct page *page) 772 { 773 VM_BUG_ON_PAGE(!PageSlab(page), page); 774 SetPageActive(page); 775 } 776 777 static inline void __ClearPageSlabPfmemalloc(struct page *page) 778 { 779 VM_BUG_ON_PAGE(!PageSlab(page), page); 780 __ClearPageActive(page); 781 } 782 783 static inline void ClearPageSlabPfmemalloc(struct page *page) 784 { 785 VM_BUG_ON_PAGE(!PageSlab(page), page); 786 ClearPageActive(page); 787 } 788 789 #ifdef CONFIG_MMU 790 #define __PG_MLOCKED (1UL << PG_mlocked) 791 #else 792 #define __PG_MLOCKED 0 793 #endif 794 795 /* 796 * Flags checked when a page is freed. Pages being freed should not have 797 * these flags set. It they are, there is a problem. 798 */ 799 #define PAGE_FLAGS_CHECK_AT_FREE \ 800 (1UL << PG_lru | 1UL << PG_locked | \ 801 1UL << PG_private | 1UL << PG_private_2 | \ 802 1UL << PG_writeback | 1UL << PG_reserved | \ 803 1UL << PG_slab | 1UL << PG_active | \ 804 1UL << PG_unevictable | __PG_MLOCKED) 805 806 /* 807 * Flags checked when a page is prepped for return by the page allocator. 808 * Pages being prepped should not have these flags set. It they are set, 809 * there has been a kernel bug or struct page corruption. 810 * 811 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's 812 * alloc-free cycle to prevent from reusing the page. 813 */ 814 #define PAGE_FLAGS_CHECK_AT_PREP \ 815 (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON) 816 817 #define PAGE_FLAGS_PRIVATE \ 818 (1UL << PG_private | 1UL << PG_private_2) 819 /** 820 * page_has_private - Determine if page has private stuff 821 * @page: The page to be checked 822 * 823 * Determine if a page has private stuff, indicating that release routines 824 * should be invoked upon it. 825 */ 826 static inline int page_has_private(struct page *page) 827 { 828 return !!(page->flags & PAGE_FLAGS_PRIVATE); 829 } 830 831 #undef PF_ANY 832 #undef PF_HEAD 833 #undef PF_ONLY_HEAD 834 #undef PF_NO_TAIL 835 #undef PF_NO_COMPOUND 836 #endif /* !__GENERATING_BOUNDS_H */ 837 838 #endif /* PAGE_FLAGS_H */ 839